This invention relates to an improved cooling box to be applied to a cooling system of steel making blast furnaces.
An explanation will be made to the prior art in reference to the attached drawings for clarification.
As cooling facilities to be applied to the blast furnace, there has been an exchangeable cooling box other than a cooling stave, which is as seen in FIG. 1. The shown cooling box 10 is in general produced by casting brass and provided with 2 to 6 water passages 11, and these passages are communicated with each other. The cooling box 10 is, as shown in FIG. 2, furnished within a wall of a furnace shaft 20 for protecting environmental bricks 21 and an iron shell 22 by passing the water therein. The brick is reduced in its thickness at a certain wearing rate as life of the furnace grows. FIGS. 3(a) and (b) show wearings of the bricks within the two furnaces. Lower parts of the shafts at 10 m from tuyeres were measured, and FIG. 4 shows in graph remaining thicknesses of the bricks 21 which are made in accompany with working period of year in the two furnaces. When the bricks 21 in the furnace become reduced in thickness as the working time goes, the cooling box 10 exposes its pointed end within the furnace as illustrated in FIG. 5. The exposed part is directly attacked by gas (1000.degree. to 1400.degree. C.) within the furnace, and the heat load from the furnace becomes higher to cause danger of loss by the molten material as seen in a flow chart in FIG. 6. If the heat load is suddenly effected on the furnace wall by slipping (i.e., sudden slide of the burden), the cooling water is boiled in the cooling box 10, and further a phenomenon of water hammer occurs by steam hunting in the cooling box 10. If a communicating pipe (lead pipe.flange packing) to the cooling box is damaged by the water haxmer phenomenon, water supply to the cooling box 10 is stopped and the cooling box 10 is lost by the molten material. When the water is boiled in the cooling box, pressure is lost by causing steam in water discharging pipes, so that pressure in the cooling box is made higher than pressure for supplying the cooling water, and the supply water to the cooling box 10 is stopped, and the cooling box 10 is molten away at last.
The cooling box 10 is prevented from melting loss by increasing the amount of the water supply, or applying mortar or other refractories to the furnace inside. The former of increasing the water supply heightens the electric fee for pumping the water, so that pig iron costs up inevitably. The cooling box 10 can be prevented from melting loss, however the exposed part at the pointed end thereof is bent downwardly, and this phenomenon considerably hinders smooth dropping of the burden in the furnace. In general, if life of the furnace is long, the furnace condition is unstable as much and the ratio of fuel is increased. These undesirable matters depend upon irregular dropping of the burden.
From these viewpoints, the conventional cooling box 10 as shown in FIG. 1 has recently been provided with multi-passages for a new blast furnace to be given initial kindling, having the cooling system in dependence upon the cooling box.
The damaged cooling box 10 may be substituted, unfortunately the bricks 21 in vicinity of the cooling box are much destroyed when substituting, and in case substitution were much, the iron shell 22 would be cracked.
The present invention has been provided to remove said defects involved about the prior cooling box. In the invention, the cooling box is divided into a plurality of chambers in a direction toward the furnace, and each of the cooling chambers is communicated with a water pipe, so that the water is charged and discharged independently. If the cooling box is effected with loss by melting as the bricks become wearing, it is no longer necessary to exchange the cooling box. The amount of the cooling water may be controlled.
Actual embodiment of the invention will be explained in reference to the attached drawings.